Before the last update, it was possible to get system and sector informations by loading via dofile lua/maps/systemNmap.lua .
Now (1.8.630/1.8.630.1 on Linux) it returns nil for any system you request that way.

I don't know if it was collateral damage or intentionally included, but the lua/maps path was restricted from plugin access, because the lua path was restricted.

Given further expansion of the galaxy, exploration mechanics and so on, it doesn't really make much sense for plugins to read directly from the game data.

If there's a desire for a more restricted and intentional API, to yield specific information based on a character's individual progression and awareness, then that could be described on Suggestions.